The present invention relates to the field of downhole oil, gas, and/or geothermal exploration and more particularly to the field of drill bits for tool strings of such exploration.
Since the beginning of downhole drilling, a lot of time and resources have been invested in developing an optimal drill bit for a downhole tool string. Because of the enormous expense associated with running a drill rig, the operational quality of a drill bit may provide substantial economic benefits.
Today's drill bits generally serve at least two purposes. Using rotary energy provided by the tool string they bore through downhole formations, thus advancing the tool string further into the ground. They also function to dispense drilling mud pumped through the tool string that lubricates parts and washes cuttings and formation material to the surface.
The prior art contains references to drill bits with sensors or other apparatus for data retrieval. For example, U.S. Pat. No. 6,150,822 to Hong, et al discloses a microwave frequency range sensor (antenna or wave guide) disposed in the face of a diamond or PDC drill bit configured to minimize invasion of drilling fluid into the formation ahead of the bit. The sensor is connected to an instrument disposed in a sub interposed in the drill stem for generating and measuring the alteration of microwave energy.
U.S. Pat. No. 6,814,162 to Moran, et al discloses a drill bit, comprising a bit body, a sensor disposed in the bit body, a single journal removably mounted to the bit body, and a roller cone rotatably mounted to the single journal. The drill bit may also comprise a short-hop telemetry transmission device adapted to transmit data from the sensor to a measurement-while-drilling device located above the drill bit on the drill string.
U.S. Pat. No. 6,913,095 to Krueger discloses a closed-loop drilling system utilizes a bottom hole assembly (“BHA”) having a steering assembly having a rotating member and a non-rotating sleeve disposed thereon. The sleeve has a plurality of expandable force application members that engage a borehole wall. A power source and associated electronics for energizing the force application members are located outside of the non-rotating sleeve.